“Radio frequency identifier (RFID) system”, which allows for information exchanges to and from IC tags that store IC information by near field communication via wireless means, such as electromagnetic fields and radio waves, is mainly utilized for merchandise information control and theft prevention in the US, Europe, and other countries. Also in Japan, the need for RFID begins to increase. Resist inks are used in production of IC tags for use in RFID.
IC tags are typically produced as follows: a coil pattern for constituting a circuit pattern is printed on a metal foil with a resist ink using a masking method, the printed portion is optionally subjected to UV curing or heat curing, and then the metal foil is immersed in an acidic or alkaline etchant to remove portions that are unnecessary for the circuit pattern by etching, thereby producing the desired circuit pattern (for example, see PTL 1: JP-A-2015-65384).
A type of such a process where a printed coat for constituting a resist in etching is cured by heat typically requires baking at 170° C. to 200° C. with an oven. In such a case, a lower temperature in baking is desired from the viewpoints of energy saving and cost reduction. On the other hand, in the case of baking at a lower temperature, negative effects, such as reduced adhesiveness of the printed coat to a substrate metal foil or reduced acidic etching resistance in the step of acidic etching, are apt to be caused. There is a need for a resist ink adaptable to low temperature baking that maintains both the adhesiveness to a metal foil and the acidic etching resistance even under low temperature conditions at an oven temperature of 150° C.